H2-or H2/N2-plasma treatment to prevent organic ILD degradation

ABSTRACT

Degradation of organic low-k interlayer dielectrics during fabrication is substantially prevented or significantly reduced by treatment with a H 2 - or H 2 /N 2 -containing plasma. Embodiments include treating a SiCOH, such as Black Diamond®, ILD with an H 2  or H 2 /N 2  plasma after deposition, after forming a damascene opening therein and/or after CMP but prior to capping layer deposition.

RELATED APPLICATIONS

This application contains subject matter similar to subject matterdisclosed in copending U.S. patent application Ser. No. 09/731,006 filedon Dec. 7, 2000.

TECHNICAL FIELD

The present invention relates to a method of manufacturing asemiconductor device exhibiting reduced capacitance loading. The presentinvention has particular applicability in manufacturing high density,multi-level semiconductor devices comprising sub-micron dimensions andexhibiting high circuit speed.

BACKGROUND ART

Interconnection technology is constantly challenged to satisfy the everincreasing requirements for high density and performance associated withultra large scale integration semiconductor devices. The speed ofsemiconductor circuitry varies inversely with the resistance (R) andcapacitance (C) of the interconnection system. The higher the. value ofthe R x C product, the more limiting the circuit speed. As integratedcircuits become complex and feature sizes and spacings become smaller,the integrated circuit speed becomes less dependent upon the transistoritself and more dependent upon the interconnection pattern. Thus, theperformance of multi-level interconnects is dominated by interconnectcapacitance at deep sub-micron regimes, e.g., less than about 0.12micron. The rejection rate due to integrated circuits speed delays insub-micron regimes has become a limiting factor in fabrication.

The dielectric constant of materials currently employed in themanufacture of semiconductor devices for an inter-layer dielectric (ILD)ranges from about 3.9 for dense silicon dioxide to over 8 for depositedsilicon nitride. The value of the dielectric constant expressed hereinis based upon a value of one for a vacuum. In an effort to reduceinterconnect capacitance, dielectric materials with lower values ofpermitivity have been explored. The expression “low-k” material hasevolved to characterize materials with a dielectric constant less thanabout 3.9. One type of low-k material that has been explored are a groupof flowable oxides which are basically ceramic polymers, such ashydrogen silsesquioxane (HSQ). Such polymers and their use are disclosedin, for example, U.S. Pat. No. 4,756,977 and U.S. Pat. No. 5,981,354.HSQ-type flowable oxides have been considered for gap filling betweenmetal lines because of their flowability and ability to fill smallopenings. HSQ-type flowable oxides have been found to be vulnerable todegradation during various fabrication steps, including plasma etching.Methods involving plasma treatment have been developed to address suchproblems attendant upon employing HSQ-type flowable oxides as a gapfilling layer, as in the U.S. Pat. No. 5,866,945 and U.S. Pat. No.6,083,851.

There are several organic low-k materials, typically having a dielectricconstant of about 2.0 to about 3.8, which may offer promise for use asan ILD. As used throughout this disclosure, the term “organic” isintended to exclude HSQ type materials, e.g., flowable oxides andceramic polymers, which are not true organic materials. Organic low-kmaterials which offer promise are carbon-containing dielectric materialssuch as FLARE 20™ dielectric, a poly(arylene) ether, available fromAllied Signal, Advanced Micromechanic Materials, Sunnvale, Calif.,Black-Diamond™ dielectric available from Applied Materials, Santa Clara,Calif., BCB (divinylsiloxane bis-benzocyclobutene) and Silk™ dielectric,an organic polymer similar to BCB, both available from Dow Chemical Co.,Midland, Mich.

In attempting to employ such carbon-containing low-k materials ininterconnect technology, as for gap filling or as an ILD, it was foundthat their dielectric constant became undesirably elevated as a resultof subsequent processing. For example, the dielectric constant of BCBwas found to increase from about 2.6 to greater than about 4. It isbelieved that such an increase occurs as a result of exposure to anoxygen (O₂) plasma stripping technique employed to remove photoresistmaterial after formation of an opening in a dielectric layer, as, forexample, a via hole or dual damascene opening for interconnecting metalfeatures on different metal levels. U.S. Pat. No. 6,030,901 discloses amethod of addressing such a degradation problem by stripping aphotoresist mask by using a H₂N₂ plasma.

There exists a need for methodology enabling the use of low-kcarbon-containing dielectric materials as an ILD in high density,multi-level interconnection patterns. There exist a particular need formethodology enabling the use of such low-k materials while avoidingtheir degradation from various fabrication steps subsequent todeposition.

DISCLOSURE OF THE INVENTION

An advantage of the present invention is a method of manufacturing asemiconductor device exhibiting reduced parasitic RC time delaysemploying carbon-containing (i.e., organic) dielectric materials havinga low dielectric constant.

Additional advantages and other features of the present invention willbe set forth in the description which follows and in part will beapparent to those having ordinary skill in the art upon examination ofthe following or may be learned from the practice of the presentinvention. The advantages of the present invention may be realized andobtained as particularly pointed out in the appended claims.

According to the present invention, the foregoing and other advantagesare achieved in part by a method of manufacturing a semiconductordevice, the method comprising: forming an organic layer having anexposed surface; and treating the exposed surface with a plasmacontaining hydrogen (H₂) or H₂ and nitrogen (N₂).

Embodiments of the present invention comprise depositing an ILD of anorganic material, such as SiCOH containing Si—H bonds, and treating thesurface with a H₂/N₂ plasma. Subsequently, a damascene opening is formedin the ILD exposing internal surfaces and the exposed internal surfacesare also treated with the N₂/H₂ plasma. After plasma treating theinternal surfaces, the damascene opening is filled with a metal, and theoverburden is planarized, as by chemical-mechanical polishing (CMP),leaving an exposed upper surface of the ILD. The exposed upper surfaceof the ILD is also treated with the N₂/H₂ plasma before capping layerdeposition. Plasma treatments of the organic ILD in accordance with thepresent invention at various times during the interconnect processsubstantially prevents or significantly reduces degradation of theorganic ILD, such as an undesirable increase in the dielectric constant,undesirable shrinkage and an undesirable shifting in the reflectiveindex, as a result of subsequent processing steps, such as O₂ ashing,etching, exposure to elevated temperature and/or exposure to variouschemicals, e.g., CMP slurries.

Additional advantages of the present invention will become readilyapparent to those skilled in this art from the following detaileddescription, wherein embodiments of the present invention are described,simply by way of illustration of the best mode contemplated for carryingout the present invention. As will be realized, the present invention iscapable of other and different embodiments, and its several details arecapable of modifications in various obvious respects, all withoutdeparting from the present invention. Accordingly, the drawings anddescription are to be regarded and illustrative in nature, and not asrestrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a Fourier transform infra red (FTIR) spectrum plot showingdegradation of an organic film as a result of oxygen (O₂) ashing.

FIG. 2 is a FTIR illustrating prevention of organic film degradation inaccordance with an embodiment of the present invention.

FIG. 3 is a graph illustrating prevention of organic ILD degradation inaccordance with an embodiment of the present invention.

FIGS. 4-7 schematically illustrate sequential phases of a method inaccordance with an embodiment of the present invention.

DESCRIPTION OF THE INVENTION

The present invention addresses and solves problems attendant uponconventional multi-layer interconnect devices, particularly parasitic RCtime delays. The capacitance, both layer-to-layer and within-layer, isprimarily attributed to the film properties of the ILD. The presentinvention enables the use of various low-k organic carbon-containingdielectric materials for ILDs without or with significantly reduceddegradation of the dielectric materials.

Upon attempting to employ various organic carbon-containing materials,such as SiCOH, e.g., Black-Diamond™, it was found that degradation ofimportant properties occurred at various times during fabrication. Forexample, upon experimentation and investigation, it was found thatdegradation manifested itself in various ways, such as by an increase inthe dielectric constant, shrinkage of the deposited layer and a shift inthe refractive index. It was found that Black-Diamond™ underwent anincrease in the dielectric constant from about 3 to about 5, a shrinkageof about 20% and a significant change in the refractive index.Manifestly, such adverse degradation not only increases capacitance butadversely impacts device reliability.

The present invention addresses and solves such degradation problemsattendant upon employing organic carbon-containing low-k materials forILDs, i.e., increased dielectric constant, shrinkage and shift inrefractive index, by treating exposed surfaces of the organic materialwith a plasma containing H₂ or a plasma containing both H₂ and N₂, atvarious times during fabrication to substantially prevent orsignificantly reduce degradation which would otherwise occur by virtueof subsequent processing, such as etching, O₂ ashing, CMP, exposure toelevated temperatures and/or exposure to various chemicals.

The present invention is particularly applicable to interconnecttechnology involving damascene techniques. Thus, embodiments of thepresent invention comprise depositing an organic carbon-containing,low-k material, such as SiCOH, and treating the exposed upper surfacewith a H₂ or H₂/N₂ plasma. Subsequently, openings are formed in the ILDby damascene techniques, including dual damascene techniques. Theopenings formed in the ILD can be via holes which are subsequentlyfilled with a metal, such as copper (Cu) or a Cu alloy, to form a viainterconnecting upper and lower metal lines, or a contact hole in whichcase the Cu or Cu alloy filled contact hole electrically connects afirst metal layer with a source/drain region in the semiconductorsubstrate. The opening in the ILD can also be a trench, in which casethe filled trench forms an interconnection line. The opening can also beformed by a dual damascene technique, in which a via/contactcommunicating with a line is simultaneously formed by metal deposition.

In accordance with embodiments of the present invention, the opening istreated with the H₂ or H₂/N₂ plasma prior to filling with a metal.Subsequent to metal deposition and CMP, the upper surface of the ILD isagain treated with the plasma containing H₂ or H₂/N₂ prior to depositingthe capping layer. Thus, embodiments of the present invention comprisetreating exposed surfaces of a carbon-containing organic ILD at variousphases from deposition to final encapsulation thereof with a H₂ or H₂/N₂plasma, e.g., on at least three different occasions, to preventdegradation which would otherwise occur during subsequent processing.Such degradation can occur from plasma etching to form the damasceneopening, O₂ ashing to remove the photoresist employed to form theopening, CMP or exposure to elevated temperature and/or variouschemicals conventional as during cleaning of the opening, during CMP andduring capping layer deposition.

A wide variety of organic carbon-containing low-k materials can beemployed as an ILD in accordance with embodiments of the presentinvention, including various polyimides, BCB, FLARE™, Silk™, andBlack-Diamond™ dielectrics. Other suitable low-k dielectrics includepoly(arylene)ethers, poly(arylene)ether azoles, parylene-N, polyimides,polynapthalene-N, polyphenyl-quinoxalines (PPQ), polyphenyleneoxide,polyethylene and polypropylene. It was found particularly suitable toemploy SiCOH which exhibits a dielectric constant of about 3 andtypically contains carbon in the amount of about 16 to about 18 at. %,e.g., about 17 at. %. silicon in an amount of about 15 to about 18 at.%, e.g., about 17 at. %, oxygen in an amount of about 28 to about 30 at.%, e.g., about 29 at. %, and hydrogen in an amount of about 36 to about38 at. %, e.g., about 37 at. %. SiCOH contains SiC, SiH, CH and SiOHbonding.

It was found that treatment of an organic carbon-containing low-k ILD inaccordance with embodiments of the present invention employing a H₂ orH₂/N₂ plasma substantially prevents or significantly reducesdegradation, such that the dielectric constant, shrinkage and refractiveindex do not undergo a change in excess of 3%. It was also found thattreatment of dielectric materials such as SiCOH, with the H₂ or H₂/N₂plasma substantially prevented reduction in the number of Si—H bondsduring subsequent processing.

Given the present disclosure and the objectives of the presentinvention, the conditions during plasma treatment with H₂ or H₂ and N₂can be optimized in a particular situation. For example, it was foundsuitable to treat exposed surfaces of an organic carbon-containing low-kILD, such as SiCOH, with a plasma containing H₂ at: a H₂ flow rate ofabout 150 to about 350 sccm; a pressure of about 3 to about 5 Torr; anRF power of about 250 to about 450 watts; a spacing (distance betweenthe wafer and shower head from which the gases exit) of about 500 toabout 800 mils; and a temperature of about 380° C. to about 420° C., forabout 15 to about 35 seconds. It was also found suitable to treatexposed surfaces of the organic carbon-containing low-k ILD with aplasma containing hydrogen and nitrogen at: a N₂ flow rate of about3,000 to about 7,000 sccm; a H₂ flow rate of about 150 to about 350sccm; a pressure of about 3 to about 5 Torr; an RF power of about 250 toabout 450 watts; a spacing of about 500 to about 800 mils; and atemperature of about 380° C. to about 420° C., for about 15 to about 35seconds.

Plasma treatment of a carbon-containing, organic low-k ILD in accordancewith embodiments of the present invention can be performed on exposedsurfaces prior to any subsequent processing which may degrade theproperties of the ILD. Optimum results are achieved by treating allexposed surfaces of the carbon-containing organic ILD with the H₂ orH₂/N₂ plasma prior to any subsequent processing which would otherwiseresult in degradation of the ILD properties, e.g., increase thedielectric constant, shrinkage and/or shift in the refractive index.

Experimentation was conduct on SiCOH to demonstrate the effectiveness ofplasma treatment in accordance with embodiments of the presentinvention. FTIR plots were taken of a SiCOH film as deposited andsubsequent to O₂ ashing, and the results plotted in FIG. 1. It should beapparent that degradation of the as-deposited SiCOH film occurred due toO₂ ashing. A SiCOH film was then deposited, treated with an N₂/H₂ plasmaand then subjected to O₂ ashing. FTIR plots taken of the SiCOH film asdeposited, subsequent to N₂/H₂ plasma treatment and subsequent to O₂ashing are depicted in FIG. 2, and show virtually no change, i.e.,virtually no degradation, due to O₂ ashing because of the prior N₂/H₂plasma treatment.

Further testing was conducted on SiCOH to demonstrate changes in thecomponents and dielectric constant, and the data plotted in FIG. 3. As acontrol, a SiCOH film was not subject to O₂ ashing. As a second control,a SiCOH film was subjected to O₂ ashing. As an embodiment of the presentinvention, the SiCOH film was subjected to 40 seconds of H₂/N₂ plasmatreatment. As shown in FIG. 3, the present invention significantlyprevents degradation of the SiCOH film, prevents a significant increasein the dielectric constant and prevents a significant change in thethickness of the deposited film.

Further experimentation on SiCOH was conducted. The controls comprise aSiCOH film on which O₂ ashing was not conducted and a SiCOH film onwhich O₂ ashing was conducted. Plasma treatments included H₂ as well asH₂/N₂, NH₃ and NH₃/N₂. The results consistently showed that plasmatreatment in accordance with embodiments of the present inventionsubstantially prevented or significantly reduced degradation in theSiCOH structure, an increase in the dielectric constant and a change inthe thickness of the SiCOH film.

A method in accordance with an embodiments of the present invention isschematically illustrated in FIGS. 4 through 7, wherein like featuresare denoted by like reference numerals. Adverting to FIG. 4, referencenumeral 51 denotes a lower metal feature formed in ILD 50 overlying asubstrate or wafer (not shown). ILD 50 can comprise any conventionaldielectric material or an organic carbon-containing low-k materialpreviously treated in accordance with the present invention with a H₂ orH₂N₂ plasma. An organic carbon-containing low-k ILD 52, such as SiCOH,is deposited over ILD 50 and metal feature 51. In accordance with anembodiment of the present invention, the upper exposed surface 53 ofSiCOH ILD 52 is treated with a H₂ or H₂/N₂ plasma 54 to substantiallyprevent or significantly reduce degradation during subsequentprocessing. Such subsequent processing would include forming aphotomask, etching to form an opening, removing the photoresist andcleaning the opening, which would otherwise degrade SiCOH ILD 52.

Adverting to FIG. 5, opening 60, e.g., a trench, is formed by aconventional damascene technique, leaving exposed side surfaces of SiCOHlayer 52 as well as exposed upper surfaces of ILD 50. In accordance withembodiments of the present invention, such exposed surfaces are treatedwith the H₂ or H₂/N₂ plasma 63 to substantially prevent or significantlyreduce degradation of SiCOH layer 52 and ILD 50, particularly if ILD 50is also a carbon-containing low-k material. Such plasma treatment isperformed prior to photoresist stripping and solvent cleaning whichwould otherwise degrade the SiCOH ILD 52 (and ILD 50 particularly if itis made of a organic carbon-containing low-k material).

Subsequently, as shown in FIG. 6, a metal is deposited into trench 60 toform a conductive line 70, such as Cu or a Cu alloy. In implementing Cuinterconnect technology, a barrier layer and seed layer are typicallydeposed in accordance with conventional practices. Subsequent to metaldeposition, CMP is conducted to form a planarized surface exposing theupper surface 71 of SiCOH layer 52. Such CMP exposes ILD 52 to chemicalsthat would have caused degradation but for prior plasma treatment.

At this point, prior to subsequent processing, the exposed upper surface71 of SiCOH layer 52 is treated with the H₂ or H₂/N₂ plasma 72 toprevent degradation which would otherwise occur during subsequentprocessing, including deposition of a capping layer and exposure toelevated temperatures. As shown in FIG. 8, capping layer 80, such assilicon nitride, is then deposited to encapsulate metal 70 as well asSiCOH layer 52.

It should be apparent from FIGS. 4 through 7 that embodiments of thepresent invention include treating exposed surfaces of an organiccarbon-containing low-k material, such as SiCOH, which an H₂ or H₂/N₂plasma prior to processing and/or exposure to chemicals which wouldotherwise significantly degrade the characteristics of the ILD, such asincreasing its dielectric constant, reducing its thickness and shiftingits refractive index. Plasma treatment in accordance with theembodiments of the present invention using H₂ or a combination of H₂ andN₂ particularly H₂ and N₂, effectively prevents such degradation,thereby enabling the use of organic low-k dielectric material as ILDswith an attendant reduction in the RC constant, cross-talk voltage andpower dissipation between lines.

The exact mechanism involved in protecting of the organic low-k materialfrom degradation in accordance with embodiments of the present inventionis not known with certainty. However, it is believed that plasmatreatment in accordance with the present invention results in theformation of a strongly bonded thin skin on the surface of the organiclow-k material, such as a thin skin of silicon oxynitride or SiN, as ata thickness of about 20 Å to about 50 Å, which prevents degradation ofthe organic low-k material, particularly preventing an increase in itsdielectric constant.

The present invention enjoys industrial applicability in manufacturinghighly integrated semiconductor devices exhibiting increased circuitspeed and sub-micron dimensions, e.g., with a design rule of about 0.12micron or under. The present invention includes the use of variousmetals for the interconnection system, particularly Cu and Cu alloys,employing both single and dual damascene techniques.

In the preceding detailed description, the present invention isdescribed with reference to specifically exemplary embodiments thereof.It will, however, be evident that various modifications and changes maybe made thereto without departing from the broader spirit and scope ofthe present invention, as set forth in the claims. The specification anddrawings are, accordingly, to be regarded as illustrative and notrestrictive. It is understood that the present invention is capable ofusing various other combinations and environments and is capable ofchanges or modifications within the scope of the inventive concept asexpressed herein.

What is claimed is:
 1. A method of manufacturing a semiconductor device,the method comprising: forming an organic interlayer dielectric (ILD)having an exposed surface; forming a damascene opening in the ILD;filling the damascene opening with a metal; planarizing leaving an uppersurface of the ILD exposed; and treating the exposed surface of the ILDwith a plasma containing hydrogen (H₂) or H₂ and nitrogen (N₂) tosubstantially prevent or substantially reduce degradation thereof thatwould otherwise occur during subsequent processing.
 2. The methodaccording to claim 1, comprising treating the exposed surface of the ILDwith a plasma containing N₂ and H₂.
 3. The method according to claim 1,comprising treating the exposed surface of the ILD with the plasma tosubstantially prevent or substantially reduce an increase in thedielectric constant, shrinkage and/or a shift in the refractive index ofthe ILD during subsequent processing.
 4. The method according to claim1, wherein ILD contains carbon, silicon, oxygen and hydrogen.
 5. Themethod according to claim 4, wherein the ILD is SiCOH and contains Si—Hbonds.
 6. The method according to claim 5, comprising treating theexposed surface of the ILD with the plasma to substantially prevent orsubstantially reduce a reduction in the number of Si—H bonds duringsubsequent processing.
 7. The method according to claim 1, comprisingtreating the exposed surface of the ILD with a plasma containing H₂ at:a H₂ flow rate of about 150 to about 350 sccm; a pressure of about 3 toabout 5 Torr; an RF power of about 250 to about 450 watts; a spacing ofabout 500 to about 800 mils; and a temperature of about 380° C. to about420° C., for about 15 to about 35 seconds.
 8. The method according toclaim 1, comprising treating the exposed surface of the ILD with aplasma containing H₂ and N₂ at: a N₂ flow rate of about 3,000 to about7,000 sccm; a H₂ flow rate of about ₁₅₀ to about ₃₅₀ sccm; a pressure ofabout 3 to about 5 Torr; an RF power of about 250 to about 450 watts; aspacing of about 500 to about 800 mils; and a temperature of about 380°C. to about 420° C., for about 15 to about 35 seconds.
 9. The methodaccording to claim 1, comprising treating the as-deposited ILD with theplasma before subsequent processing.
 10. The method according to claim9, comprising: forming a damascene opening in the ILD, after treatingthe as-deposited ILD, exposing internal surfaces of the organic ILDwithin the opening; and treating the exposed internal surfaces of theorganic ILD with the plasma.
 11. The method according to claim 10,comprising: filling the damascene opening with a metal after plasmatreating the exposed internal surfaces of the ILD; and planarizing bychemical mechanical polishing.
 12. The method according to claim 1,comprising depositing a capping layer after treating the exposed uppersurface of the ILD with the plasma.
 13. The method according to claim10, comprising treating the exposed internal surfaces of the ILD with aplasma containing N₂ and H₂.
 14. The method according to claim 1,comprising filling the damascene opening with copper (Cu) or a Cu alloy.15. The method according to claim 8, comprising filling the damasceneopening with copper (Cu) or a Cu alloy.
 16. The method according toclaim 3, comprising plasma treating the exposed surface of the ILD toprevent the dielectric constant of the ILD from increasing more than 3%.17. The method according to claim 3, comprising plasma treating theexposed surface of the ILD to prevent the ILD from shrinking more thanabout 3%.
 18. A method of manufacturing a semiconductor device, themethod comprising: forming an organic layer having an exposed surface,wherein the organic layer is SiCOH and contains Si—H bonds; and treatingthe exposed surface with a plasma containing hydrogen (H₂) or H₂ andnitrogen (N₂).
 19. The method according to claim 18, comprising:depositing the organic layer as an interlayer dielectric (ILD); forminga damascene opening in the ILD exposing internal surfaces of the ILDwithin the opening; and treating the exposed internal surfaces of theILD with the plasma.
 20. The method according to claim 18, comprising:depositing the organic layer as an interlayer dielectric (ILD); forminga damascene opening in the ILD; filling the damascene opening with ametal; planarizing by chemical mechanical polishing leaving an outersurface of the ILD exposed; and treating the exposed outer surface ofthe ILD with the plasma.
 21. The method according to claim 20,comprising depositing a capping layer after treating the exposed outersurface of the ILD with the plasma.
 22. The method according to claim18, comprising treating the organic layer with the plasma tosubstantially prevent or substantially reduce an increase in thedielectric constant, shrinkage and/or a shift in the refractive index ofthe organic layer during subsequent processing.
 23. The method accordingto claim 18, comprising treating the organic layer with the plasma tosubstantially prevent or substantially reduce a reduction in the numberof Si—H bonds during subsequent processing.
 24. The method according toclaim 18, comprising treating the organic layer with a plasma containingH₂ at: a H₂ flow rate of about 150 to about 350 sccm; a pressure ofabout 3 to about 5 Torr; an RF power of about 250 to about 450 watts; aspacing of about 500 to about 800 mils; and a temperature of about 380°C. to about 420° C., for about 15 to about 35 seconds.
 25. The methodaccording to claim 18, comprising treating the organic layer with aplasma containing H₂ and N₂ at: a N₂ flow rate of about 3,000 to about7,000 sccm; a H₂ flow rate of about 150 to about 350 sccm; a pressure ofabout 3 to about 5 Torr; an RF power of about 250 to about 450 watts; aspacing of about 500 to about 800 mils; and a temperature of about 380°C. to about 420° C., for about 15 to about 35 seconds.
 26. The methodaccording to claim 18, comprising: depositing the organic layer as aninterlayer dielectric (ILD); and treating the as-deposited ILD with theplasma before subsequent processing.
 27. The method according to claim26, comprising: forming a damascene opening in the ILD, after treatingthe as-deposited ILD, exposing internal surfaces of the ILD within theopening; and treating the exposed internal surfaces of the ILD with theplasma.
 28. The method according to claim 27, comprising: filling thedamascene opening with a metal after plasma treating the exposedinternal surfaces of the ILD; planarizing by chemical mechanicalpolishing leaving an upper surface of the ILD exposed; and treating theexposed upper surface of the ILD with the plasma.
 29. The methodaccording to claim 22, comprising plasma treating to prevent thedielectric constant of the organic layer from increasing more than 3%.30. The method according to claim 22, comprising plasma treating toprevent the organic layer from shrinking more than about 3%.
 31. Themethod according to claim 18, comprising treating the exposed surfacewith a plasma containing N₂ and H₂.
 32. The method according to claim27, comprising treating the exposed internal surfaces of the ILD with aplasma containing N₂ and H₂.
 33. The method according to claim 20,comprising filling the damascene opening with copper (Cu) or a Cu alloy.34. The method according to claim 18, comprising treating the exposedupper surface of the ILD with a plasma containing N₂ and H₂.